Work vehicles having internal combustion engines, such as tractors, road graders and the like, often operate in environments in which the air is filled with dust, dirt and grit. With such vehicles there is often more than the normal concern about cleaning the air used for combustion.
Because of such concern, such vehicles often include special baffling structures to effect the flow of air prior to the entry of such air into the intake ducts leading to the air cleaners on the internal combustion engines. Air cleaners, of course, have filters to remove very fine particulates so that the air entering the combustion chambers will be relatively clean. Without the use of special baffling structures to effect the air flow prior to its entry into the air cleaner duct and then into the air cleaner, coarser particulates can quickly clog the filters in the air cleaner. Without such baffling structures, air filters have to be changed much more frequently.
In a typical arrangement for a tractor with a frontmounted engine, the air cleaner is located above the engine block and an air cleaner duct extends from the air cleaner forwardly over the fan and over the radiator to terminate in a forward position near the upper edge of the tractor grille. Air flows into the distal end of the air duct at that location and from there into the air cleaner. One or more baffles, typically metal pieces, are attached to the tractor near the grille in position to prevent the air passing through the grille from going directly into the air duct.
The action of the engine fan, of course, causes air to flow at a relatively high rate through the grille, and the baffling is positioned to require such air coming through the grille to change both its speed and direction by going through a tortuous path before being admitted into the open distal end of the air-intake duct. The change or changes in both direction and speed of the air flow caused by such baffling causes the coarser and heavier dust and dirt particulars to "fall out," so that particulates entering the air-intake duct and then the air cleaner are primarily very fine particulates.
The use of such baffling structures to create a tortuous path for intake air causes unnecessary structural complexity and inaccessibility under the hood of the work vehicle, and adds unnecessary cost. There has been a need for an improved air-intake system for work vehicles. More specifically, there has been a need for a simple air-intake duct which eliminates the need for vehicle-mounted baffle structures for creation of a tortuous air path. There has been a need for an improved duct which accomplishes these purposes without just transferring the baffles and complexity to the duct itself.